RESUMO
A continuation of a single-individual culture of Hymenolepis diminuta WMS ill from generations 37 to 66 revealed a very high infective ability of cysticercoids which is reflected in the percentage of tapeworms detected in relation to the number of cysticercoids given to rats (94.4%). The tapeworms investigated revealed a significant increase in the abundance of type 0p3a proglottids (those with no testes on the poral side and 3 on the aporal) in tapeworms of successive generation groups. Each group of tapeworms analysed statistically belonged to three successive generations and numbered 31-34 individuals. The mean abundances of 0p3a type proglottids in tapeworms of the first groups studied in experiment, including generations 37-39 and 40-42 were 9.2% and 9.5%, respectively. The last studied groups, including generations 61-63 and 64-66 had higher mean numbers of type 0p3a proglottids, at 11.1% and 11.5%, respectively. The quantitative figures of 1p3a type proglottids amounted to 1.6% and 1.3% in first generation groups and in the last two groups 0.8% and 1.0%, respectively. The probable cause of this significant (P < 0.01) relative increase in the numbers of 0p3a type proglottids and decrease (P < 0.01) in the numbers of 1p3a type proglottids was the deliberate selection of maternal tapeworms characterized by numbers of 0p3a type proglottids greater and 1p3a type proglottids smaller than the average for their generation.
